which I usually do a few times a week. At work it sits out in the sun but I have tinted windows and always put up a windshield shade. I've only cleaned them a few times with a leather cleaner product that leaves no shine(that's the way I prefer it). Never put any type of protectant product on it.
Heres a crappy iphone pic I snapped right now over four years later(z is very dirty right now):